1. Field of the Invention
The present invention relates to apparatuses for spraying etchant solution and, more particularly, to an apparatus for spraying an etchant solution onto a preformed printed circuit board.
2. Description of Related Art
Recently, as the electronic appliances are becoming smaller in size and diversified in function, printed circuit boards (PCBs) widely used in such electronic appliances are required to have greater circuit density and reliability.
Usually, printed circuit boards are etched using a chemical etching process. The chemical etching process uses an apparatus to spray an etchant solution onto the preformed printed circuit boards and includes the following steps: providing a copper clad laminate (CCL); forming a photoresist layer on the copper clad laminate by screen printing or photographic methods; placing the copper clad laminate in an etching bath; conveying the copper clad laminate by a feed roller in a running direction and spraying the etchant solution evenly onto both an upper surface and a bottom surface of the copper clad laminate by a number of nozzles mounted on the apparatus for spraying the etchant solution to etch the copper uncovered by the photoresist layer so as to form the printed circuit board.
This chemical etching process is advantageous in that it is both cheap and it allows a high level of automation. However, problems can be caused by the way in which the nozzles of the apparatus for spraying the etchant solution have the same spray pressure when spraying the etchant solution onto the printed circuit board. During spraying, the sprayed etchant solution on the periphery of the printed circuit board flows off and is replaced by new etchant solution, but the sprayed etchant solution on the central portion of the printed circuit board cannot easily flow away. This leads to the sprayed etchant in the central area of the printed circuit board being inadequately replenished by the new etchant solution since the old etchant solution congregates in the central area, as a result the central area of the printed circuit board is etched unevenly.
What is needed, therefore, is an apparatus for spraying an etchant solution which can be used to uniformly etch the printed circuit board.